Container and method of forming the same



Nov. 5, 1968 BALOCCA ET AL 3,409,200

CONTAINER AND METHOD OF FORMING THE SAME Filed Aug. 26, 1966 INVENTORS 41/7950 find/917314106614 (am/e4 5s W/ZA/AM sew/1.0

United States Patent ABSTRACT on THE DISCLOSURE A container having an end closure which may be removed by removing a plastic strip which is incorporated in the top end seam. The plastic strip is adhered to the container body at the top end and is pressed inwardly against the body by a smoothly rounded hollow curl at the lower end of the closure flange, which thins the strip so that there are thicker portions thereof above and below it to thereby provide a clinched scam, the seam release strip being indented into the body to create a somewhat loose snap fit engagement between the end and the body and permit the end to be used as a reclosure.

The present invention relates to easy-opening containers and has particularreference to a container construction wherein a removable plastic strip is incorporated in the top end seam of the container to provide for the complete detachment of the top closure member of the container'without destruction or mutilation of either the container body or the top closure member.

In present-day packaging technology, great emphasis is placed on the development of containers which incorporate self-contained easy-opening features in order to relieve the consumer of the burden of having to use separate opening devices or tools to effect the opening of the container. I

Substantial success has been attained in this area by providing cans and containers wherein removable pre-cut or pre-scored portions are formed in metal end closure members in order to provide access to the container contents. In such containers, the non-removed portion of the metal end remains secured to the container body after the container has been opened. While this type of opening feature has been well received and is excellent for many products, it is in some instances not completely satisfactory since it does result in raw metal edges and in somewhat restricted dispensing openings in the containers.

Other easy-opening container constructions'employ tear strips or pull strings which are disposed in the container body. Here again, such containers are often not completely satisfactory since they result in at least partial destruction of the body wall and, in many instances, in a diminution of the height of the body and a resultant reduction in its capacity.

The present invention provides an easy opening container construction which avoids all of the disadvantages of these other constructions in that it makes possible a full-open container in which the complete top closure member can be readily detached by the consumer without tools and without any mutilation or tearing of either the container body or the top closure member.

This is accomplished by securing a plastic seam release strip to the outer surface of the upper end portion of the container body prior to the seaming of the top end closure member thereto. Thereafter, the top end closure member is seamed onto the pre-assembled body and strip structure in such manner that a smooth, inwardly curled edge of the cover member indents itself into the strip and simultaneously indents the strip into the body wall, thereby forming a crimped end seam in which the strip forms an integral holding member.

3,409,200 Patented NOV The strip is formed of a tough, flexible, tear'resistant thermoplastic resinous material, such as high, medium; or low density polyethylene, polypropylene, or copolymers of ethylene with monomers such as vinyl acetate or ethylacrylate, which is deformable and extensible so that the portion of the strip which is pressed against the container body by the curled edge of the cover member is thinned out in the pressure area which is disposed below but parallel to the top edge of the strip to thus'enhance'the holding power of the strip.

One end of the strip' is formed into a pull tab which enables the consumer to pull the strip outwardly and away from the end seam. The strip, being formed of a tough, extensible plastic, does not tear under the pulling pressure but instead elongates and thins out as it is pulled through the pressure area. By virtue of this thinning of the strip, the strip easily passes through the space between the cover curl and the container body, thereby greatly reducing the holding power of the seam by changing the'connection between the top closure member and the container body to a straight friction seal which the consumer canreadily overcome by manually lifting off the cover member to gain access to the container contents and, if desirable or necessary, subsequently re-establish by replacing the cover member on the body to utilize it as a friction reclosure.

An object of the invention of the provision of an easyopening container which is attractive in appearance and can be easily opened without the use of opening tools.

Another object is the provision of an easy open container wherein means are provided to permit complete detachment of the top closure member without mutilation of either the body or the top closure member.

'Yet another object of the invention is the provision in such a container of a snap-fit reclosure feature.

Still another object of the container is the provision of a method of forming such a container.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

Referring to the drawings: 7

FIG. 1 is a perspective view of a container body having a plastic seam release strip secured in place thereon prior to the application thereto of the top end closure member;

FIG. 2 is a perspective view of a completed container embodying the body and strip assembly of FIG. 1; I

FIG. 3 is a view similar to FIG. 1 showing the upper portion of a container body having a modified form of plastic seam release strip adhered to it;

FIG. 4 is an enlarged sectional detail taken substan tially along the line 44 in FIG. 1, and showing addi-' tionally in dot and dash lines a portion of the top closure member in position on the body prior to being seamed thereto;

FIG. 5 is an enlarged sectional detail taken substantially along the line 5--5 in FIG. 2;

FIG. 6 is a side elevation of the upper portion of th container of FIG. 2 showing the seam release 'strip par tially pulled out of the seam during the container opening operation; i

FIG. 7 is a sectionaldetail on an enlarged scale taken substantially along the line 7-7 in FIG. 6; and

FIG. 8 is a vertical sectional detail on an enlarged'scale taken substantially along the line 88 in FIG. I

As a preferred .and exemplary embodiment of the in stant invention, FIG. 2 discloses a container 10 having a tubular body 12 which is formed of a oompressiblematerial such as fibreboard. The body 12 may be'of any suitable type, as for example, a convolutely wound body, :a' lap seam body or a spirally wound body, and may com label plies (not shown) which may be made of metal foil 7 I or plastic film which may or may not be coated with a protectivevarnish or lacquer. While the body 12 is shown as being Cylindrical, it may have any desirable cross sectional configuration. It may also be formed of plastic, glass or metal.

The bottom end of the body 12 is closed by means of an imperforate metal bottom closure member 14 which is secured to the body in a seam 16 of any suitable type, while'theupper end of the body 12 is closed by means of an i'rnperforate metal top closure member 18.

Prior'to the'application of the top closure member 18, a thin plastic strip 20, which shall for the purposes of this specification be called a seam release strip, is secured to the upper marginal edge portion of the body 12 by a layer of an adhesive 22 (see FIG. 4) which maybe of any suitable type, such as a pressure sensitive adhesive or a thermoplastic adhesive, and 'which should have low peel resistance characteristics relative to the surface of the body'12 to'which it adheres.

As seen in FIG. 1, the upper edge of the seam release strip 20 is substantially coplanar with the upper edge of the body 12, and the opposed end edges 24, 26 of the strip 20 are disposed in substantially abutting relationship. While these edges may be slightly spaced apart, it is important that they do not overlap each other, at least in the upper portion of the strip, for reasons hereinafter explained.

, The strip 20 is made of a thermoplastic resin such as high, medium, or low density polyethylene, polypropylene, or copolymers of ethylene with menomers such as vinyl acetate or ethylacrylate, and may vary in thickness from about 3 or 4 mils to 20 mils, depending on the specific container dimensions and requirements and on variables in the other container components. The strip 20 should be deformable .and extensible, and should have a tearrelsistance sufficiently high so that it does not tear during the opening operation. Its surfaces should preferably be smooth and have a relatively low coefficient of friction. It will be understood that the strip may be formed of a single type of plastic or may comprise a lamination of one or more materials which can be selected to tailor the strip to specific container applications. It has been determined that a strip of high density polyethylene and having a thickness of mils is excellent for many container applications.

After the seam release strip has been adhered to the body 12, the top closure member 18 is positioned on the body 12 and seamed in place. As shown in dot and dash lines in FIG. 4, the top closure member 18 is formed with a substantially vertical countersink wall 28 which extends into the body and lies inwardly of and in frictional engagement with the inner surface of the marginal top end portion of the body 12. The member 18 is initially formed with on outwardly projecting flange 30 which overlies the top edge of the body 12 and terminates in an inwardly extendin'gopen curl 32.

After the top closure member 18 and the body 12 have been thusrelatively positioned, the flange 30 .and ourl 32 of the end 18 are reshaped by means of first and second operation seaming rolls (not shown) in such manner as to bend the flange 30 downwardly and inwardly around the top marginal portion of the body 12 to the configuration shown in FIG. 5. This reshaping operation reforms the initially open curl 32 into a substantially closed curl 34 which presses inwardly against the seam release strip 20 and clamps the strips 20 and the body 12 against the countersink wall 18. It will be understood that the wall 18 is supported by .a seaming chuck (not shown) during the seaming operation.

As best seen in FIG. 5, the seaming pressure which is transmitted by the curl 34 causes the generally non-compressible plastic strip 20 to extend and thus results in actual physical thinning of the material of the strip 20 is the annular area of contact 35 where the curl 34 engages the strip 20. In addition to this thinning of the plastic stri p 20, the seaming pressure indents a portion of the strip 20 into the fibre body 12 thereby resulting in a compression thinning of a portion 38 0f the body 12 inwardly of the curl 34 and inwardly of the thinned plastic portion 36. As a result of this thinning and indenting, the end closure member 18iis securely locked in .place onthe body-12 in what may be designated as a clinched or indented seamof a type which in a conventional-container could'not' be disrupted without the use of a container opening tool; 1:

After the top closure'member 1 8 has been thus seamed in place, the container is filled with' a product (not shown) through its opening bottom end and thereafter closed by seaming the bottom end closure member 14 in place. It will be understood, however, that under some circumstances it may be desirable to fill through the top end of the container. This can readily be accomplished by'rever'sing the order of application of the end closure members, i.e., by first seaming the bottom closure member 14 in place, then filling through the open top end of the container, and then seaming on the top closure member 18. While it will be realized that the filling operation may be effected in a factory other than the one in which the strip 20 is applied tothe body 12, thus necessitating shipment of the body 12 with the strip 20 thereon prior to the formation of the seam 40, this presents no problem since the adhesive 22 accurately and positively retains the strip 20 in place on the body 12 until such time as the top end closure member 18 is applied.

To facilitate opening of the container, one end of the strip 20 is formed into a depending pull tab 42 of suitable configuration. To open the container, the consumer need merely to. grasp the pull tab 42 between a thumb and forefinger and pull it outwardly away from the seam 40 in a substantially clockwise direction, as seen in FIG. 6. Grasping of the pull tab 42 is facilitated by the fact that the adhesive 22 is of a type which has low peel resistance so that the tab 42 can be easily stripped away from the body wall 12 by the use of a finger nail of the consumer. Ifv desired, the adhesive 22 may be omitted from all or a portion of the tab 42 to facilitate its engagement by the fingers.

When the pull tab 42 is grasped and pulled in the manner just described, pressure is applied to cause the material ofthe plastic strip 20 which is disposed above its thinned portion 36 to be pulled downwardly between the curl 34 and the compressed portion 38 of the body 12. Downward movement of the strip 20 is resisted by the fact that the portion 44 of the strip 20 within the seam 40 is of greater thickness than is its thinned portion 36, and thus is of greater thickness than the minimum spacing between the curl 34 and body 12. However, the plastic material from which the strip 20 is 'formed is extensible or elongatable, and thus the pulling pressure has the effect of causing the portion 44 of the strip 20 to elongate and to thin down to substantially the thickness of the gap between the curl 34 and compressed body portion 38 so that it passes downwardly between the curl 34 and the compressed body wall portion 38 and thereby is removed from the end seam 40. Removal of the strip 20 from the seam is facilitated by the fact that the surface of the curl 34 which contacts the strip 20 is rounded and smooth and that the raw edge of the curl 34 is spaced away from the strip 20.

As seen in FIGS. 6 and 7, the stretching or thinning out of this portion 44 of the strip 20 usually results in its being distorted into a thin, wavy configuration 45 which is indicative of a permanent distortion of the material of the strip 20. The degree of distortion will of course vary with the material from which the strip 20 is made.

Complete opening of the container is effected by pulling on the tab 42 until the strip 20 is completely stripped from the seam 40. The removal of the strip is facilitated by the fact that the adhesive 22 has low peel characteristics :whicheause, itito' olferlittleresistance test-he stripping action, which in. the, main. is apeeling .actiont ltgis of course very desirable that the adhesive 22 be selected so that it strips cleanly awayfrom'i the outer surface of the body 12 without tearing out .or mutilating any portion of this surface, which in most cases will be a label surface which should remain intact after the opening opera- 'tiorr'*to insurea=clean, attractive appearance in the opened container. To insurethe cleanstripping of the adhesive, the exterior surface of the body maybe coated with a suitable varnish or'lacquer'which is-selected to provide the desired degree of adhesion between the adhesive 22 and the body -12.--: 1"

After the pull strip has thus been remqvedtrom the seam 40, an open" gap remains 'betweenthecurl -34 and the body 12, as best seen in FIG. 8, so that the securement bet-ween the top closure 18 and the body wall 12 resides in a frictional engagement between the countersink wall 18 of the cover and the inner surface of the upper edge of the body 12. This friction fit can be readily overcome by merely pulling upwardly on the closure member 18 to remove it from the upper edge of the body 12 thereby completing the opening of the container and granting access of: its contents. If desired, the closure member 18 may thereafter be replaced on the body 12 to function as a reclosure.

It will be noted that as a result of the formation of the seam 40, the upper edge portion 46 of the body 12 preferably extends radially outwardly to a position where it just slightly overhangs the radially innermost portion of the curl 34. As a result, there is very slight interference between the body 12 and the end closure member 18. This interference is desirable since it does not appreciably hinder removal of the closure member 18, but does provide a somewhat loose snap fit engagement between the closure member 18 and the body 12 which is very desirable when the former is used as a reclosure.

FIG. 3 shows a modification of the pull tab end of the strip 20. In this version, this end of the strip 20 is extended beyond the opposite end of the strip to form an overlapping pull tab 47. In order to prevent the existence of a double thickness of any portion of the strip 20 in the area where it is gripped by the curl 34 in the end seam (which seam is partially shown in dot and dash lines in FIG. 3 and is in all respects identical to that shown in FIG. 5), the upper portion of the strip 20 is cut away along a line 48 which extends downwardly from the top of the strip 20 to a point below the curl 34 and then extends horizontally along the bottom edge of the curl 34. As a result, the ends of the strip 20 which are enclosed in the seam 40 are in substantially the same abutting relationship as are the ends of the strip shown in FIG. 1, even though the tab 47 does overlap the opposite end of the strip.

It should be realized that it would be very undesirable to have more than one thickness of the strip 20 in the pressure area 36 in any version of the container since this would at worst result in a cutting of the material of the overlapped portion of the strip 20 by the curl 34 during the seaming operation, and at best in an excess pinching of the overlapped portion of the strip 20 by the curl 34. Either situation would of course prevent or inhibit easy removal of the strip 20 from the seam 40.

It will be understood that the inside surface of the strip 20 of FIG. 3 is adhered to the body 20 by a low-peel adhesive just as is the strip 20 of FIG. 1. Desirably, the adhesive is also disposed on the inside surface of the pull tab 47 and adheres it to the underlying portion of the strip 20 so that it does not project outwardly away from the body 20 to a position where it could be inadvertently snagged in such manner as to cause premature partial removal of the strip.

It is thought that the invention and many of its attendant advantages will be understood from the forgoing description and it will be apparent that various changes may be.,,made in the, form, construction and arrangement ofthe parts of the article and that changes may be;rnade in the steps of the method described and their orderof accomplishment. without departing from the spirit and scope ofthe invention or sacrificing all of its material advantages, theform hereinbefore described being merely a preferred embodiment thereof.

1. A container comprising a tubular b dy, a Seam rele:ase.strip surrounding the outside surface of said body atone, end thereof and extending substantially to the adjacent end edge of said body, and a metal end closure member disposed on the said end of said body, said metalend closure-member having a countersink wall extending along the inner surface of said body and merging into a flange which extends around the adjacent end edge of said body and then along the outer surface of said seam release strip, said flange having at its lower end an annular, smoothly rounded and hollow inwardly projecting curl terminating in an edge spaced from and pointing away from said seam release strip, said curl pressing, at the rounded surface thereof, said seam release strip against said body along an annular pressure area of contact spaced below the said edge of said body to form a clinched end seam where the upper edge portion of said body extends radially outwardly to a position where it overhangs a portiori of said curl, said seam release strip being formed of a tough, extensible, tear-resistant plastic material which is thinned by the pressure exerted by said flange in said pressure area and is therefore thicker in the portion thereof which is enclosed in the seam above said pressure area, said seam release strip being elongated when it is pulled in a direction away from said seam to thereby enable said thicker portion to thin out and to thereby pass between said flange and said body and to be removable from said seam under digital pressure alone, said upper edge portion and said curl providing a snap fit engagement to permit said end closure member to be used to reclose said container.

2. The container of claim 1 wherein the seam release strip is adhesively secured to the body by an adhesive having low-peel characteristics relative to the body surface to which it is adhered.

3. The container of claim 1 wherein one end of said seam release strip comprises a pull tab, :and wherein that portion of the seam release strip which is engaged by said flange curl in the pressure area is disposed in non-overlapping relationship.

4. The container of claim 3 wherein one end of said seam release strip is overlapped over the other end to form said pull tab, and wherein the upper portion of said pull tab end of said strip is cut away to prevent the overlapped ends of said strip from being engaged by said flange curl in said pressure area.

5. The container of claim 4 wherein Said pull tab is adhesively secured to the underlying portion of said strip to secure it against undesirable outward projection from the side of said container.

6. The method of forming an easy-opening container comprising the steps of:

providing an open-ended container body,

adhesively securing an extensible seam release strip to the outside surface of one end of said body with an edge of said strip in substantial alignment with the adjacent edge of said body,

positioning a metal end closure member on the said end of said body with a countersink wall of said closure member disposed in engagement with the inside surface of said body and with the flange of said closure member extending outwardly over the said edge of said body,

forming said flange so that it has at its end an annular hollow smoothly rounded inwardly projecting curl, the end edge of said curl facing toward the uncurled 7 8 portion of said flange, and said flange projects gention of said seam release strip is indented into said body erally downwardly, along an annular area spaced below the edge of said body. forcing the said flange inwardly to bring said smoothly rounded hollow curl into contact with said seam re- References Cited lease strip while positioning said end edge of said 5 UNITED STATES PATENTS curl so that It is spaced from said seam release strip, and 3,142,433 7/1964 Balocca 22951 pressing the smoothly curved portion of said curl against 3330436 7/1967 slomskl "7' 22053 7 said seam release strip to press said strip against the body wall and to cause the portion of the seam re- 10 FOREIGN T F lease strip which is in the pressure area to thin out 667,939 3/1952 Great and to indent said seam release strip into said conminer b0dy THERON E. CONDON, Primal Examiner.

7. The method of claim 6 wherein the body is formed GEORGET HALL Assistant Examiner of a compressible material, and wherein said thinned por- 15 

